notificationclick.js

self.addEventListener('notificationclick', function(e) {
  // Android doesn't automatically close notifications on click
  e.notification.close();

  // Focus tab if open
  e.waitUntil(clients.matchAll({
          type: 'window'
      }).then(function(clientList) {
          for (var i = 0; i < clientList.length; ++i) {
              var client = clientList[i];
              if (client.url === '/' && 'focus' in client) {
                  return client.focus();
              }
          }

          if (clients.openWindow) {
              return clients.openWindow('/');
          }
      })();
  }));
});